<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <title>Page Title</title>
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>

</head>

<body>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/gsap/1.20.3/TweenMax.min.js"></script>

    <div id="animated-number-demo">
        <input v-model.number="number" type="number" step="20">
        <p>{{ animatedNumber }}</p>
    </div>
</body>
<script>
    new Vue({
        el: '#animated-number-demo',
        data: {
            number: 0,
            tweenedNumber: 0
        },
        computed: {
            animatedNumber: function() {
                return this.tweenedNumber.toFixed(0);
            }
        },
        watch: {
            number: function(newValue) {
                TweenLite.to(this.$data, 0.5, {
                    tweenedNumber: newValue
                });
            }
        }
    })
</script>

</html>